Parabolic waveshape generator



Un t d S e 2,917,549 a PARABOLIC WAVESHAPE GENERATOR Abraham'L. Bernstein, Metuchen, NJ., assignor to Westinghouse Electric Corporation; East Pittsburgh, Pa., 2 corporationof Pennsylvania I A 7 Filed Aug. 7, 1957, Ser. No. 676,886

2 Claims. (Cl.331'112) This invention relates to generators for producing nonatent C) resistances of the base electrode 11-emitter electrode 12 and the'collector electrode 13-base electrode 11 diodes.

, The voltage at" the terminals 24 is the integral of the cursinusoidal waves, and particularly to such generators for producing parabolic waves;

Generators of the blocking-oscillator type are known which. are capable of producing pulse type signals or sawtooth waves. In the past, in order to produce a parabolic wave, it has been the practice to integrate the sawtooth wave. d 7

Accordingly, an object of the present invention is to provide a generator which directly produces parabolic waves. 1

It is another object of the present invention to provide a generator of the blocking-oscillator type which directly produces parabolic waves. g

It is a further object. of the invention to provide a novel generator for producing non-sinusoidal oscillations.

These and other objects are effected by my invention as will readily appear from a consideration of the following detailed description, taken in conjunction with the accompanying drawing, in which:

Figure 1 is a schematiccircuit diagram'of a preferred embodiment'of the invention; and 7 Figs. 2A to 20 are graphical illustrations representing the. waveforms producedat various points in the circuit Referring to Fig. 1 in detail, the circuit shown is for producing a parabolic wave, and comprises a transistor having base, emitter and collectorelectrodes, 11, 12 and 13, respectively.. A transformer 14 having aprimary winding 15 and a secondary winding 16 is connected in such a manner to provide a regenerative feedback path between the collector electrode 13 and the base. electrode 11 of transistor 10. Primary winding 15 has twoterminals 17 and 18 and secondary winding 16 likewise has two terminals 19 and20. Connected between terminals 18 i and 19 is a resistor 21. Terminal 17 is connected to collector electrode 13 and terminal 20 is connected to base electrode 11. Connected between terminal 19'and emitter electrode 12 is a resistor 22. Connected between a capacitor 26. Terminal 18 is connected to a suitable source of operating potential B which biases collector electrode 13 in the usual manner, that is, in a non-conducting polarity with respect to base electrode 11.

rent flowing through the resistor 22. Since the time constants of the leakage transformer windings 15 and 16 with their respective leakage paths (resistor 21 plus the diode composed of collector electrode 13 and base electrode 11; resistor 22 plus the diode composed of base electrode 11 and emitter electrode 12) are large compared to the period of the waveform E, the current through the resistor 22 is linear and the output waveform is part of a parabola which is an integral of a linear function.

When the voltage across secondary winding 16 of transformer 14becomes zero (at point 27 of Fig. 2A), the base electrode ll-emitter electrode 12 diode becomes biased in the forward or conduction direction. When this occurs, the regenerative feedback due to the transformer 14 causes the transistor 10 to become heavily conductive,

biases the collector electrode 13 in a conducting polarity with respect to the base electrode 11. At this point, the gain of transistor 10 has decreased so that regenerative action ceases. Since the base electrode ll-collector electrode 13 diode is conducting, the base current of the transistor 10 decreases linearily, with a time constant determined by the transformer 14 and the resistor 21, and the emitter current of the transistor 10 decreases linearily. This emitter current is integated in the integrator circuit 23'comprising the resistor'25 and the capacitor 26 to produce the remainder of the parabola. The base voltage of the transistor 10 increases until the collector electrode 13 is again biased in a non-conducting polarity with respect to the base electrode 11 of the transistor 10. At this stage, the gain of transistor 10 increases and regenerative action is initiated which will drive the transistor 10 to cut-off and non-conduction.

In describing the preferred embodiment of my. invention I have shown an illustrative circuit utilizing a tran-.

sistor as an active element. It is to be understood that a vacuum tube could be used equally as well. Also, nu-

' merous other modifications will be apparent to those skilled in the art without departing from the spirit and scope of the invention.

' I claim as my invention:

. 1. A parabolic waveshape generator comprising a transistor having an emitter electrode, a collector electrode,

6 and a base electrode, a transformer intercoupling said collector electrode with said base electrode to provide a feedback path to cause regeneration, said transformer having a primary winding connected at one end to said col- The transformer 14 is connected with thepolarity of .itswindings 15 and 16 opposite, as indicated by dots, so 7 that a positive-feedback signal is supplied to transistor 10 when conduction occurs.

takenacross the outputterminals 24, waveformB which is taken across terminals 19 and 20, and waveform- C 1 whichis' an expanded graph (expanded around zero volts) tral.

collector electrode and a point of reference potential, a

second resistor, connected between said emitter electrode and'the. end of said secondary winding opposite said base electrode, and an integrating circuit connected between aid emitter electrode andsaid point of reference potensistor having an emitter electrode, a collector electrode,

and a base electrode, a transformer having first and second windings connected respectively to said collector electrode and said base electrode to provide a regenerative feedback path therebetween; circuit means including a source of operating potential connected to negatively bias said collector electrode with respect to said emitter electrode, a resistance voltage divider having a pair of end terminals and an intermediate terminal, with said end terminals being connected respectively to said emitter electrode and to the end of said first winding opposite said collector electrode and with said intermediate terminal being connected to the end of said second winding opposite said base electrode, and an integrating circuit connected at one end to said emitter electrode and at the other end to the positive terminal of said source for integrating periodic and linearly varying collector electrode currents to produce a substantially parabolic waveform output voltage thereacross.

References Cited in the file of this patent UNITED STATES PATENTS 2,227,075 Geiger Dec. 31, 1940 2,396,439 Schlesinger Mar, 12, 1946 2,536,804 Goldberg et a1. :.'Ian. 2, 1951 2,764,643 Sulzer Sept. 25, 1956 FOREIGN PATENTS 630.219 Great Britain Oct. 7, 1949 

